Problem: In his physics class, Christopher took 6 quizzes. His scores were 85, 97, 91, 90, 78, and 93. What was his average score on the quizzes?
Explanation: The average is the sum of his scores divided by the number of scores. There are 6 scores and their sum is $85 + 97 + 91 + 90 + 78 + 93 = 534$ His average score is $534 \div 6 = 89$.